The present invention relates to a bearing assembly for knuckle or swivel joints in general, and more particularly to ball and socket joints of very simple structure provided with a wear indicator.
Knuckle or swivel joints of the ball and socket type are commonly used in motor vehicle steering tie rod assemblies, in drag links, torque rods and like structures, in which there is a requirement for transmitting a force from a member to another while permitting one member to swivel or pivot relative to the other.
Knuckle or swivel joints of the ball and socket type consist generally of a stud terminating in a full or partial ball disposed within a socket member in swivelling slidable engagement with a conforming concave spherical segment of the socket member. The engaged bearing surfaces of the ball and of the socket are biased, or pre-loaded, towards each other such as to provie a relatively tight assembly eliminating play and rattle and automatically compensating for wear of the bearing surfaces.
Ball and socket knuckle or swivel joints are of the dry type, or of the prelubricated type without lubricator for replenishing the lubricant, or are provided with a grease fitting permitting to occasionally replenish the supply of lubricant, for example during normal servicing of a motor vehicle. Whatever the type of ball and socket joints installed on a motor vehicle, progressive wear and tear of the bearing surfaces in constant preloaded swivelling engagement gradually proceed to a state beyond the capability of the pre-load structure to compensate for wear, to the point where play and rattle begin to appear under excessive loads which are beyond the capability of the wear compensation pre-load to accommodate. Although such excessive wear, which requires replacement of the joint, may be estimated by an experienced mechanic while servicing a motor vehicle, through visual inspection of the joints, or by means of appropriate gauges, or simply by manually shaking the steering tie rod assembly, for example, and approximately judging the amount of play and rattle, and the looseness of the joints, it is evident that such a procedure of checking for wear leaves much to be desired.